(Reuters) - A federal judge has sentenced a former Philadelphia police officer to 15 years in prison for informing his half-brother that authorities were investigating him for dealing heroin.

Rafael Cordero, 53, was arrested in 2012 after authorities uncovered his relationship with David Garcia, who once ran one of the city's biggest heroin distribution rings, according to court documents.

The sentence imposed on Wednesday by U.S. District Court Judge Paul Diamond exceeded that sought by federal prosecutors.

A jury found Cordero guilty in December for obstructing justice after he told Garcia the federal Drug Enforcement Agency was surveilling his operations. He was also convicted of lying to police and the Federal Bureau of Investigation.

Until his arrest, Cordero worked in the criminal intelligence unit, where he gathered information about criminal activity and shared it with police and federal authorities, according to court documents.